Automatic electrical control for furnaces and fire alarms



p 1951 w. KAGAN 2,567,112

AUTOMATIC ELECTRICAL CONTROL FOR FURNACES AND FIRE ALARMS Filed Jan. 15, 1950 Patented Sept. 4, 1951 AUTOMATIC ELECTRICAL CONTROL FOR FURNACES AND FIRE ALARMS William Kagan, St. Louis, Mo.

Application January 13, 1950, Serial No. 138,327

2 Claims. (Cl. 200138) This invention relates to automatic electrical controls for furnaces and fire alarms for mounting in co-operative position and relation to such furnaces, and the main object of the invention is to provide an apparatus of this kind for mounting closely above a furnace, as for example upon the under side of the overhead floor joists, and thus closely subject to operation by virtue of any excess of heat arising from the over-heating of the furnace itself or any adjacent fire that might be started by such over-heating.

Another object of the invention is to provide in an apparatus of the kind referred to for controlling an electrically operated burner of a furnace and for simultaneously sounding an alarm in the event of the undue over-heating of a furnace, a suitably apertured housing for mounting immediately above the furnace, an operating shaft journaled horizontally within the housing, a mercury tube perpendicularly mounted upon the inner end of the shaft and extended horizontally, the said tube being provided or loaded with mercury adapted to run to either end of the tube as same is tilted from the horizontal for opening or closing electrical contacts seated within the ends of the tube and the connected electrical wires leading from such contacts to the burner of the furnace and to the associated alarm element, a bi-metallic thermostat ribbon mounted spirally upon the outer end of the operating shaft and attached thereto at its inner end, and thus adapted for partially rotating the shaft and tilting the mercury tube at the inner end thereof for opening and closing the connected electrical circuits to the burner and alarm, under the influence of excess heat, means for regulating the degree of heat required for operating the said thermostat ribbon and connected shaft and tube, and conventional electrical leads and connections as required for operating the elements of the invention.

With the stated objects in view, together with such additional objects and advantages as may appear from the specification, attention is now directed to the accompanying drawing as exemplifying a preferred embodiment of the invention, and wherein Figure 1 is a longitudinal vertical section through the housing an enclosed mechanism and devices as constituting the subject matter of this invention, together with the extended ends of the electrical leads and conductors.

Figure 2 is a vertical cross section on an enlarged scale, taken on the line 2-2 of Figure 1.

Figure 3 is a vertical cross section on an enlarged scale similar to that of Figure 2, taken on the 1ine 33 of Figure 1.

Figure 4 is a front elevational view, on the scale of Figures 2 and 3, showing the housing and attached cover plate and temperature indicating pointer.

Figure 5 is a detail sectional view taken on line 5-5 of Figure 1.

In practising this invention I provide a suitable housing or box 5, preferably rectangular in form, and adapted for attaching to the under side of the floor joists (not shown) immediately over a furnace (not shown), and thus positioned so as to be readily subjected to the action of excess heat such as might arise from an over-heated furnace or boiler, or from an adjacent fire caused by such furnace.

The operating devices of the invention are mounted within the housing 5, and for facilitating the entrance of heat into the housing the latter is apertured or perforated on it sides, bottom and frontal end as indicated at 5a. The frontal end of the body portion of the housing 5 is closed by a fiber insulation plate 5b, and an operating shaft 6 is journaled horizontally through the center of this plate and is supported in place by an elongated hub-like bearing element 1, the ends of which protrude at each side of the plate as at la, and through which bearin element the shaft 6 is extended and journaled, as indicated at 6a. A bi-metallic thermostat ribbon 8 is spirally mounted, as here shown in an anti-clockwise manner of coiling, upon and over this outer extended end 6a of the shaft 6,-the inner end of this ribbon 8 being secured in any conventional manner to the shaft 6, as indicated at 8a, and the outer end of the ribbon being bent back reversely upon itself to form an adjustment hook 8b, provided for adjusting and regulating the tension of the ribbon 8 for the purpose later pointed out.

A temperature setting finger 9 is frictionally looped as at 9a upon the outer extended end 1a of the bearing hubl, so that while the finger may be turned upon the hub it will be frictionally held thereon at any adjusted position. A latch pin 9b is seated in the outer free end of the finger 9, and is extended perpendicularly out and seated at its outer end within the hook 811 of the bi-metallic ribbon 8. By this arrangement the tensioning and consequent temperature adjustment of the ribbon 8 may be increased or decreased as desired, in the manner and for the purpose later pointed out.

A cupped cover plate It is removably secured by set screws Ila upon the frontal end of the housing 5, said screws being threadedly set into cars 50 turned inwardly from the sides of the housing. The outer face of this cover plate is calibrated to form a temperature dial Ill). The plate is bored through centrally as at llc for passing the outer end of the shaft 6.

A temperature indicating pointer I2 is frictionally looped as at I200 upon the outer end 6a of the shaft 6 in co-operative relation to the temperature setting finger 9 and the dial III). A shaft adjustment knob 6c is provided at the extremity of the shaft 6 outwardly of the pointer [2. The inwardly extended end 61) of the shaft 6 is threaded as shown for engaging the bored central web of a tube holding bracket I3 which is locked in place thereon by nuts I4. The bracket l 3 is made of fiat strip spring metal with its ends turned and forked outwardly in spaced relation and formed into a pair of arcuate clamps I3a for engaging a glass mercury tube l5 at its medial point. The tube I5 is partitioned centrally as at l5a, and plugs I51) of insulation material are fitted into the tube ends, thus forming the mercury cells 5 50, Mid. The tube is positioned in the holding clamp so as to extend transversely of the housing 5. Pairs of electrical lead-in wires and lead-out wires are inserted at their adjacent ends through the plugs 52) at the ends of the tube I5, and are seated in spaced contact buttons [Ge-46f within the ends of the tube. The lead-in wires Ifia, 160, are connected with and extended from any source of electrical energy, while the lead-out wires l6b, Hid, run to and operate respectively the burner of the furnace and the fire alarm. Thus the mercury cells 150 and I501 are connected in series respectively with the furnace burner and fire alarm. Equal portions of mercury Ila, llb are placed in the cells #50, led, these said portions occupying a relatively small space therein, and the balance of such space in the cells is filled with an inert gas for the purpose of preventing oxidation of the mercury. For adjusting and setting the temperature indicating pointer l2 and the temperature setting finger 9, the cover plate H may be removed by removing the screws i la.

From the construction shown it is apparent that as the mercury tube ['5 is tilted vertically at its ends in either direction, through the partial rotation of the operating shaft 6, one of the portions of mercury will flow inwardly of the tube and rest upon the partition l5a, thus opening the connected electrical circuit, While the other portion of mercury in the opposite end of the tube will fiow down upon the contacts at that end for bridging the same and thus closing the connected electrical circuit thereat.

For the purposes of illustration it is shown herein that the mercury cell IE is connected with the burner side of the unit, and that the mercury cell ld is connected with the fire alarm side of the unit. In the use of the apparatus the shaft '6 may be turned manually as desired by turning the adjustment knob 60. Thus the burn erside of the unit would be set to operational position by partially rotating the shaft 6 to turn the mercury cell I50 downward for flowing the mercury portion Ha onto the contacts [6e and thus closing the circuit through the burner. 'The temperature setting finger 9 and the temperature indicating finger I2 are then set at the points desired upon the heat indicating dial I la of the cover H, and this temperature setting is placed at a point or degree somewhat above the usual or normal degree of heat as required from the furnace in the warming of the home. Then in the event of the over-heating of the furnace, or in case of fire resulting therefrom, the excess heat generated will enter the housing 5 and act upon the spiral bi-metallic ribbon 8. and will cause this ribbon to expand and spread and tend to unwind, and since the outer end of the ribbon is held stationary by the finger 9 and pin 9a, the inner end of the ribbon as attached to the shaft 6 operates to partially rotate this shaft, thus tilting the mercury cell l5c upward and opening the circuit to the burner, and simultaneously tilting the mercury cell l5d downward, thus flowing the mercury portion llb therein down upon the contact 16 at that end, for closing the circuit through the fire alarm element of the unit. The apparatus thus performs a two-fold purpose in closing off the burner and sounding the fire alarm.

While the bi-metallic thermostat ribbon 8 is here shown as spirally wound in an anti-clockwise direction upon the outer end of the shaft 6, the same could of course be wound clock-wise, with corresponding alterations being made in the associated elements. Likewise the ribbon 8 could be constructed so as to contract towards the shaft 8, instead of expanding and spreading laterally, if so desired. The essential requirement in such ribbon would be that by virtue of its bi-metallic composition of metals having different co-efliciencies of expansion under heat, so as to tend to rotate the shaft 6 in one direction or the other for tilting the tube l5 in manner above pointed out, and with the stated results of stopping the burner and sounding the fire alarm. Furthermore the described apparatus might be mounted within the hot air chute of a hot air furnace and heating system, if desired, in lieu of mounting same directly over the furnace itself, the electrical wiring being extended ac cordingly.

It is thought that from the foregoing description the construction and operation of the invention will be fully understood, and while I have here shown and described a preferred embodiment of the invention and specific structural features thereof, the same may be changed or modified as desired, within the scope of the appended claims.

I claim:

1. An automatic electrical control and alarm for. a furnace for opening a circuit to the furnace burner and closing a circuit to an alarm responsive to an increase in the ambient temperature about the furnace, comprising in combination, a housing adapted to be supported adjacent the furnace and having apertures to admit air from about the furnace, an insulating plate mounted in the housing, a hub mounted through and extending at its opposite ends to opposite sides of the plate, a shaft journaled in said hub, a spiral bi-metallic thermostat ribbon coiled around one end of the shaft and located adjacent the apertures in the housing, means securing the inner end of the ribbon to the shaft, a temperature setting finger frictionally mounted on the hub and having a pin, the outer end of the ribbon being attached to said pin whereby uncoiling and recoiling of the ribbon will turn the shaft in opposite directions and whereby adjustments of the temperature setting finger will adjust the ribbon, a bracket secured to the opposite end of the shaft, a glass tube aflixed in said bracket, said tube being closed at its ends and partitioned intermediate said ends dividing the tube into separate and insulated mercury cells, a quantity of mercury in each cell, and contacts entering the opposite ends of the tube for selective bridging-by the mercury in said cells to control the burner and alarm circuits responsive t0 the tilting of the tube incident to opposite rotational movement of the shaft.

2. In a device according to claim 1, a cover removably mounted 'overfthe frontal end of the housing and about the spiral ribbon thermostat, a. calibrated dial on said cover, the adjacent frontal end of the shaft also extending through the cover at the center of said dial, a temperature indicating pointer frictionally mounted on 6 the shaft to play over the said dial, and a knob on the exposed end of the shaft.

WILLIAM KAGAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,770,479 Cramblet July 15, 1930 1,847,035 Shivers Feb. 23, 1932 1,930,062 Rutenber Oct. 10, 1933 2,244,347 Rickmeyer June 3, 1941 2,244,348 Rickmeyer June 3, 1941 Rickmeyer June 3, 1941 

